1. Field of the Invention
Example embodiments of the present invention relate generally to a board structure, a ball grid array (BGA) package and method thereof and a solder ball and method thereof.
2. Description of the Related Art
Conventional leads may be used as external connection terminals for semiconductor packages. More recently, ball-grid array (BGA) packages, which may include solder balls, may be employed instead of leads as external connection terminals. Conventional BGA packages may include a higher fabrication density (e.g., a higher number of external connection terminals in a smaller surface area) as compared to conventional lead packages, and further may be more easily mounted on a board. Conventional BGA packages may also aid in reducing a fabrication size of semiconductor packages.
FIG. 1 is a cross-sectional view illustrating a conventional BGA package 10. Referring to FIG. 1, the BGA package 10 may be a fine pitch ball grid array (FBGA) package 10. A semiconductor chip 14 may be mounted on a printed circuit board 12 with an adhesive tape. Pads (not shown) of the semiconductor chip 14 may be connected to bond fingers of the printed circuit board 12 through wires 18. The semiconductor chip 14 and the wires 18 on the printed circuit board 12 may be sealed by an encapsulation resin 16 (e.g., an epoxy mold compound (EMC)). Beneath the printed circuit board 12, solder balls 20 may be attached as external connection terminals.
FIG. 2 is a flowchart illustrating a method for fabricating the conventional BGA package 10 of FIG. 1. Referring to FIG. 2, a printed circuit board for BGA fabrication upon which a semiconductor chip may be mounted may be provided (at S10). The semiconductor chip may be mounted on the printed circuit board using an adhesion element such as adhesive tape (at S20). A wire bonding process may be performed to connect pads of the semiconductor chip to bond fingers of the printed circuit board through wires (at S30). After the wire bonding process is completed, a molding process may be performed to mold both the semiconductor chip and the wires on the printed circuit board using an encapsulation resin (at S40). Solder balls may be attached beneath the printed circuit board (at S50).
FIG. 3 is a cross-sectional view illustrating the conventional BGA package 10 of FIG. 1 mounted on a board 40. Referring to FIG. 3, solder balls 20, which may function as external connection terminals beneath the board 40 may adhere to circuit patterns 30 on the board 40 (e.g., with an adhesive) to form an electrical connection between the board 40 and the BGA package 10. Here, an under-fill (not shown) such as epoxy may fill in any remaining space between the board 40 and the BGA package 10.
However, in the BGA package 10 of FIGS. 1-3, defects (e.g., cracks of the solder balls) may arise due to a difference in coefficients of thermal expansion (CTE) between different materials positioned in proximity to where the solder balls 29 may adhere. Thus, the solder balls may, in certain cases, detach or fail to attach sufficiently to the printed circuit board. Further, because scaling down solder ball sizes may increase a severity or quantity of solder ball defects, it may be difficult to reduce solder ball sizes without compromising fabrication quality.